The following relates generally to wireless communication, and more specifically to overhead reduction in millimeter wave (mmW) systems.
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include fourth generation (4G) systems such as a Long Term Evolution (LTE) systems or LTE-Advanced (LTE-A) systems, and fifth generation (5G) systems which may be referred to as New Radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform-spread-OFDM (DFT-S-OFDM). A wireless multiple-access communications system may include a number of base stations or network access nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE).
A base station may transmit a block of symbols (e.g., orthogonal frequency division multiple (OFDM) symbols) on a channel (e.g., physical downlink shared channel (PDSCH)) that may be received by a UE. In a multipath environment, two or more symbols may traverse paths of different lengths and reach the UE at different times. As a result, the UE may start to receive one symbol while still receiving a previous symbol. The overlap between when different symbols are received is referred to as inter-symbol interference (ISI) and may degrade the ability of the UE to successfully receive and decode each of the symbols.
Conventional wireless communication systems may decrease the effects of ISI by providing a guard interval where nothing is transmitted between the transmission of each symbol. Another conventional solution is to use a cyclic prefix or a cyclic suffix. The cyclic prefix or the cyclic suffix may be a cyclic repetition of the block of symbols in a head or a tail of the block. Guard interval, cyclic prefix, or cyclic suffix are techniques to deal with ISI in a frequency selective channel, and may help a receiver equalize and/or demodulate each block of symbols separately. Cyclic prefix may refer to adding a copy of an ending portion of a symbol to a beginning of the symbol. Cyclic suffix may refer to adding a copy of a beginning portion of a symbol to an end of the symbol. A receiver may typically discard the cyclic prefix or cyclic suffix. Although, the conventional techniques support reduction of ISI, conventional techniques detrimentally add overhead and decrease throughput. For instance, guard interval is overhead that separates the symbols in time but reduces the number of symbols that can be transmitted within a time interval.